Fracture anisotropy in silicon single crystal

In this study the effect of crystallographic orientation on fracture toughness and the fracture path of silicon single crystal was investigated. Vickers microhardness indentation was used to introduce cracks along various crystallographic orientations on the (110), (001), and (11̄1) planes. The fracture toughness variation was found to follow the symmetry of the indentation axis with no distinct correlation with the elastic constants. The observations made suggest that the inclination angle of cleavage planes relative to the indent plane affects the fracture path and toughness significantly. Prestraining decreased the hardness and improved the toughness without a modification of fracture path.